Valve control systems are used to operate one or more valves. For example, an irrigation system may comprise several circuits with the water flow through each of the circuits being controlled by a separate main valve.
In the valve control system control shown in my U.S. Pat. No. 2,252,125, a wiper or actuator rotates through a series of stations and operates a pilot valve at each of these stations. The pilot valves operate main valves, which control water flow through the various circuits of the irrigation system.
A similar valve control system, which provides for adjusting the length of time of watering at each circuit, is shown in my U.S. Pat. No. 2,372,324. The concept of variable timing for each of the irrigation circuits is most desirable. However, in my U.S. Pat. No. 2,372,324, the variable timing is obtained through the use of a stacked series of timing cams which can be selectively raised into operative engagement with a cam for operating the pilot valves. This construction is relatively complex and inflexible in that it requires one timing cam for each timing program, a mechanism to move the timing cams, and specially constructed service valves. This prior art system also cannot provide infinite asjustability in the timing at each station.